/*
 * Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.security.authentication;

import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;

/**
 * Processes an {@link Authentication} request.
 * 认证管理器，它是整个认证的入口，其定义的认证接口authenticate()接收一个Authentication对象作为参数。AuthenticationManager它只是提供了一个认证接口方法，
 * 因为在实际使用中，我们不仅有账户密码的登录方式，还有短信验证码登录、邮箱登录等等，所以它本身不做任何认证，其具体做认证的是ProviderManager子类，
 * 但正如我们说过的认证方式有很多，如果仅仅依靠ProviderManager本身来实现authenticate()接口，那我们要支持这么多认证方式不得写多少个if判断，
 * 而且以后如果我们想要支持指纹登录，那又不得不在这个方法内部加个if，这种不利于系统扩展的写法肯定是不可取的，所以ProviderManager本身会维护一个List<AuthenticationProvider>
 * 列表 ，用于存放多种认证方式，然后通过委托的方式，调用AuthenticationProvider来真正实现认证逻辑的。
 * 而Authentication就是我们需要认证的信息（当然不仅仅只包括账户信息），通过authenticate()接口认证成功后返回的Authentication就是一个被标识认证成功的对象
 * @author Ben Alex
 */
public interface AuthenticationManager {

	/**
	 * Attempts to authenticate the passed {@link Authentication} object, returning a
	 * fully populated <code>Authentication</code> object (including granted authorities)
	 * if successful.
	 * <p>
	 * An <code>AuthenticationManager</code> must honour the following contract concerning
	 * exceptions:
	 * <ul>
	 * <li>A {@link DisabledException} must be thrown if an account is disabled and the
	 * <code>AuthenticationManager</code> can test for this state.</li>
	 * <li>A {@link LockedException} must be thrown if an account is locked and the
	 * <code>AuthenticationManager</code> can test for account locking.</li>
	 * <li>A {@link BadCredentialsException} must be thrown if incorrect credentials are
	 * presented. Whilst the above exceptions are optional, an
	 * <code>AuthenticationManager</code> must <B>always</B> test credentials.</li>
	 * </ul>
	 * Exceptions should be tested for and if applicable thrown in the order expressed
	 * above (i.e. if an account is disabled or locked, the authentication request is
	 * immediately rejected and the credentials testing process is not performed). This
	 * prevents credentials being tested against disabled or locked accounts.
	 * @param authentication the authentication request object
	 * @return a fully authenticated object including credentials
	 * @throws AuthenticationException if authentication fails
	 */
	Authentication authenticate(Authentication authentication) throws AuthenticationException;

}
